The present invention relates to an electronic ballast for driving a fluorescent lamp or the like, and more particularly to a new topology ballast that has only one switch in its oscillating part.
FIG. 1 is a simplified schematic diagram of a conventional ballast circuit. As shown, the PFC (power factor correction) stage receives and rectifies AC power with power factor correction. Two switches M1 and M2, which are power MOS devices in this example, are connected in series to form a half bridge and are so controlled as to apply an oscillating voltage to a LC resonant tank circuit to drive the lamp.
It would be desirable to improve upon the conventional half-bridge structure, by reducing the number and size of key components, as compared to conventional designs.